Apparatuses and methods for detecting the production of methamphetamine

ABSTRACT

A system for detecting a gas released during production of methamphetamine in a residential building includes a sensor. The sensor is attachable to a part of the residential building. The sensor outputs a signal in response to detection of a concentration of the gas. The system includes a communication link. The communication link receives a signal from the sensor and is configured to produce an output in response to the signal

RELATED APPLICATIONS:

This application is a continuation of co-pending U.S. patent applicationSer. No 131134,676 entitled “Apparatuses And Methods For Detecting theProduction of Methamphetamine,” filed on Jun. 13, 2011 U.S. patentapplication Ser. No 13/134,676 entitled “Apparatuses And Methods ForDetecting the Production of Methamphetamine,” is hereby fullyincorporated by reference.

BACKGROUND OF THE INVENTION 1. Field of Invention

The invention relates generally to detecting combustible gas innon-industrial locations, and more specifically to apparatuses andmethods for covertly detecting and reporting the production ofmethamphetamine.

2. Art Background

Methamphetamine is a powerfully addictive stimulant, which can be easilyproduced in illicit laboratories and is generally considered the fastestgrowing illicit drug, in the United States. Methamphetamine use comeswith psychological and physical dangers to the user: all of which hasbecome a big problem to society.

Various methods can be used to make methamphetainine. Such methodsinclude reducing ephedrine or pseudoephedrine to methamphettimine viathe iodine-red phosphorus method or the ammonia-lithium method.Alternative methods include: reducing ephedrine or pseudoephedrine tomethamphetamine via catalytic hydrogenation, and reductive animation ofphenyl-2-propanone with aluminum amalgam. These methods producecombustible gas as a by-product of methamphetamine production. One suchcombustible gas is Phosphine. Production of combustible gas can lead toexplosions, tires, death and sever injury all of which have become a bigproblem,

Methamphetamine laboratories can be easily setup in private indoorspaces frequently used private indoor spaces are residential livingspaces such as homes, apartments, motel rooms, garages, storage lockers,basements, camping trailers, motor homes, etc. Explosions and firesoccurring in these locations have resulted in death, severe injury, andhave destroyed property. Chemicals residuals from methamphetamineproduction collect on the inside surfaces of these indoor spaces, suchas the walls, carpets, ceilings, etc. and on materials wheremethamphetamine is manufactured. Occupants can get sick and/or die frompost exposure to contaminants. Specialized hazmat teams must be used todecontaminate or remove contaminated materials, otherwise the buildingsmust be destroyed. All of this has presented a host of problems

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may best be understood by referring to the followingdescription and accompanying drawings that are used to illustrateembodiments of the invention. The invention is illustrated by way ofexample in the embodiments and is not limited in the figures of theaccompanying drawings, in which like references indicate elements.

FIG. 1A illustrates a concentration diagram for a combustible as

FIG. 1B illustrates a system for detecting methanaphetamine production,according to embodiments of the invention.

FIG. 2 illustrates a mounting location according to embodiments of theinvention.

FIG. 3 illustrates a plurality of sensors, according to embodiments ofthe invention.

FIG. 4A illustrates a concentration level as a function of time,according to embodiments of the invention.

FIG. 4B illustrates a second concentration level as a function of time,according to embodiments of the invention.

FIG. 5 illustrates a method for processing data collected from acombustible has sensor, according to embodiments of the invention

FIG. 6 illustrates a method for detecting methamplietamine production,according to embodiments of the invention.

FIG. 7 illustrates a block diagram of a computer system (data processingdevice such as a computer, smart phone, tablet computer, etc.) in whichembodiments of the invention may be used.

FIG. 8 illustrates a network environment in which embodiments of thepresent invention may be implemented

DETAILED DESCRIPTION

In the following detailed description of embodiments of the invention,reference is made to the accompanying drawings in which like referencesindicate similar elements, and in which is shown by way of illustration,specific embodiments in which the invention may be practiced. Theseembodiments are described in sufficient detail to enable those of skillin the art to practice the invention In other instances, well-knowncircuits, structures, and techniques have not been shown in detail inorder not to obscure the understanding of this description. Thefollowing detailed description is therefore, not to be taken in alimiting sense, and the scope of the invention is defined only by theappended claims.

Apparatuses and methods are described fur detecting the production ofmethamphetatnine.

Production of methamphetamine results in the use of flammablesubstances. These flammable substances are released into the atmospherein a gaseous state. Some examples of gaseous flammable substancesreleased during production of ethampbetamine are ammonia, acetone, ethylalcohol. Coleman fuel, lighter fluid, toluene, diethyl ether, phosphine,etc.

Combustible gases are flammable within a range of concentration know asthe explosive or flammable range. The explosive range is defined by alower explosive limit (LEL) and an upper explosive limit (UEL).Concentration of gas e,g., volume percentage of a gas is often expressedby those skilled in the art as parts per million (PPM).

FIG. 1A illustrates, generally at 100, a concentration diagram for acombustible gas. With reference to FIG. 1A, a concentration by volumepercentage for a combustible gas is illustrated at 102, with limits of0% and 100%. A lower explosive linait (LEL) is indicated at 106 and anupper explosive limit (LEL) is indicated at 108. Between these limits ofconcentration, a combustible mixture exists at 112. With oxygen and anignition source combustion will occur. Below the LEL 106 the mixture istoo lean for combustion; this range of concentrations is indicated at110. Above UEL 108, the mixture is too rich for combustion, this rangeof concentrations is indicated at 114.

Each gas has its own LEL and UEL. Values for LEL and UEL for some commongases are shown Table 1, directly below:

TABLE 1 LEL and UEL for several combustible gases GAS LEL UEL Acetone(CH3)2CO 2.15%  13.0% Ethyl Alcohol CH2H5OH 3.3% 19.0% Methane CH4 5.0%15.0% Phosphine PH3 1.8% unknown Toluene C7H8 1.2%  7.0%

Sensors made for detecting combustible gases below LEI: are typicallyscaled from 0-100% of the LEL when referring to gas concentration Inthis detailed description of embodiments, percentages given will followwith the designation of “LEL” when the percentage refers to percentageof LEL. When the percentage s meant to refer to volume the word “volume”will follow. Gas concentration is equivalently stated in parts permillion (PPM), which is a volume percentage. For example, referring toTable 1 above, Acetone reaches its lower explosive limit of 2.15% whichis equivalently stated as 21,500 PPM, noting that 1 part in 100 (1%) isequivalent to 10,000 parts in 1,000,000 (10,000 PPM),

Catalytic bead type sensors are used to detect concentrations ofcombustible gas below the LEL of the gas. Catalytic bead type sensorsburn a small amount of the gas on the surface of the bead to obtain ameasure of gas concentration. If the concentration of the has is abovethe UEL, then Catalytic head type sensors will not render an accuratereading of gas concentration. Two other types of sensors are used tomeasure high gas concentrations; these are Thermal Conductivity (TC) andNon Dispersive infrared (NDIR) sensors.

NDIR sensors are typically not exposed directly to the gas of interest,do not need oxygen to be present, and do not combust the gas in order tomeasure gas concentration. NDIR sensors will operate across the fullmeasuring range of gas concentration from 0 to 100% volume, Limitationis that a given NDIR sensor doesn't detect all flammable gases.

IC sensors are based on the principle that gases differ in their abilityto conduct heat. If a sample gas has a different thermal conductivitythan the reference gas, the temperature of the active filament willchange as compared to the reference element. A reading is obtained thatis proportional to the gas concentration of interest. IC sensors can beused to measure concentrations of a variety of gases and the IC sensordoes not need oxygen to operate. Advantages of TC sensors is that likethe NDIR sensors, TC sensors can detect gas concentrations across thefull measurement range 0 to 100% volume. Limitation is that a given TCsensor doesn't detect all flammable gases.

Several other technologies are used to build sensors for detectingcombustible gas such as “Metal Oxide Semiconductor” for detectingHydrogen, “Galvanic Cell” for detecting Oxygen, and “Electrochemical”for detecting Hydrogen Sulfide and Carbon Monoxide (solid statesensors). These sensors use LEL or PPM for measuring concentration ofthe gas or gases detected. Some combustible gases given off during theproduction of methamphetamine are petroleum based volatile organiccompounds (VOC) such as Acetone, Ethyl Alcohol, Methane, Toluene, etc,some of which are listed in Table 1. Other combustible gases given offduring methamphetamine production are organophosphorus compounds such asPhosphine (Table 1). Thus, in various embodiments, sensors used todetect combustible gas or gases given off during methamphetamineproduction are referred to as VOC sensors.

Most industry standard combustible gas sensors are powered by 24 voltsdirect current and provide an output signal of 4 to 20 mA or 0 to 10volts which is proportional to the concentration of the gas detected. Insome cases combustible gas sensors provide discreet on/off state outputsand are often configured with one or more relays that operate when apreset concentration level of gas is detected. A normally closed relaycontact on the sensor output relay can be used to detect tampering atthe measurement site. In this case tampering would deprive power to therelay which would open the contact and look like a signal, therebyalerting the system that a signal had been acquired. While suchtampering would not necessarily mean that methamphetamine was inproduction it would alert the system operator that the property shouldbe inspected.

Sensors for detecting combustible gases are commercially available fromcompanies such RKI Instruments, Inc. (Union City Calif.); PEMTECH, Inc,(Sugar Land, Tex.); General Monitors, Inc (Lake Forest, Calif.) SierraMonitor Corporation (Milpitas Calif.), etc,

FIG. 113 illustrates generally at 150, a system for detectingmethamphetamine production, according to embodiments of the invention.With reference to FIG. 1B, a sensor 154 is connected to a communicationlink 156. A combustible gas 152 is sensed by the sensor 154. In oneembodiment, the sensor 154 outputs a signal when the concentration ofgas reaches a predefined level. In another embodiment, the sensor 154outputs a signal which is proportional to the concentration of asmeasured by the sensor. The signal output from the sensor 154 is inputto a communication link 156. Communication link 156 connects with aremote site 162 via a communication network 160.

In various embodiments, the communication network is a telephone lineThe sensor 154 together with communication link 156 dials a remote siteby telephone connection. The remote site 162 can be any remote sitereachable by telephone connection, such as a telephone, a fax machine,etc, in various embodiments, the communication link 156 is incorporatedwith the sensor 154 into a package 158. In other embodiments, the sensor154 and the communication link 156 are packaged separately and are inelectrical communication with each other as required. In someembodiments, such communication with a remote site performs a remotealarm function to alert an appropriate party that methamphetamine isbeing produced in the vicinity of the sensor 154.

In some embodiments, the sensor is connected to a local alarm system(not shown). The local alarm system provides an alarm when a predefinedcondition is reached. In one embodiment, a predefined condition ismeasurement of a particular gas concentration. In other embodiments, thealarm system is remote as described above in order to provide a covertsystem for detecting the presence of methamphetamine production.

In other embodiments., communication link 156 provides an internetconnection via communication network 160, which allows a user via aremote site 162 to access the output of sensor 154. In some embodiments,remote site 162 is a computer with Internet access running anapplication program that can provide warnings when predefined levels aremeasured by the sensor 154, thereby providing a remote alarm functionfor the user.

In yet other embodiments, the communication link 156 can provide acellular phone connection to communicate information from the sensor 154to a ser at a remote site 162. In such embodiments, the remote site 162is a device enabled with mobile phone service, e.g., a mobile phone, amobile computer with mobile phone functionality, etc. The remote sitecan be under the control of the owner of the property on which thesensor 154 is located or the remote site can be at a law enforcementcenter such as a police station or the remote site can be a centerdesigned to receive and monitor input from a plurality of sensors ateither one location at a plurality of locations. 100351 The sensor 154and or communication link 156 can be located in a private residence,monitored by the system and the remote site 162 can be located at anydistance from the site being monitored. In various embodiments, it isdesirable to create a covert monitoring system for methamphetamineproduction,

FIG. 2 illustrates a mounting location, generally at 200, according toembodiments of the invention. With reference to FIG. 2, an indoor spaceis illustrated at 202. In one or more embodiments, such a space isreferred to as a residential indoor space. The residential indoor spacecan be any type of indoor space that provides a level of privacy to theoccupants and limits the view of the interior of the space from theoutside. Since methamphetamine production is an illegal activity, thoseindividuals who participate in such activity desire privacy to avoidnotice and arrest by law enforcement officials. Thus, for purposes of anon-limiting illustration, the residential indoor space 202 can be butis not limited to: a house, an apartment, a trailer, a motor home, asgarage, an outbuilding, a storage locker, a boat, etc. As used in thisdescription of embodiments, “residential” does not exclude commercial.Therefore, a residential indoor space includes such locations as storagefacilities that rent storage spaces to individuals or to businessentities.

A sensor 204 is located proximate to the structure that provides theindoor space 202. It is preferable to locate the sensor 204 out of plainsite from occupants of the indoor space 202. This is done to preventoccupants of the indoor space from tampering with the sensor 204. Thesensor 204 can be located in an air return duct for a forced hot airheating system or a return air duct for a cooling system that isassociated with the indoor space 202. Alternatively, the sensor 204 islocated in an attic space or in a basement space. When locating thesensor 204 in an attic space location near an air duct is advantageoussince gas given off within the indoor space will be drawn into the atticvia the duct which will permit measurement by the sensor 204.

The sensor 204 can be built into a ceding fixture disguised to look likea fire alarm. Such a mounting configuration would provide power andwires for the sensor's output signals. Alternatively, if a wirelesstransmitter is located with the sensor in the ceiling mount the need toprovide a hardwired signal path is eliminated.

Alternatively, the sensor 204 can be built into a surface of the indoorspace, e.g., wall or ceiling and located proximate to an opening in thesurface such as a light fixture, or electrical outlet. Location of thesensor 204 proximate to a light fixture or an electrical outlet permitsthe combustible gas to reach the sensor 204. Alternatively, the sensor204 can be built into a medicine cabinet inside a bathroom. In yet otherinstallations the sensor 204 is built into the cabinets of a kitchen,bathroom, or laundry room. It is preferable to locate the sensor 204 atany place that is not in plain sight of occupants of the indoor spaceand in such an orientation that gas produced inside of the indoor spacecan reach the sensor 204.

A sensor 206 can also be located externally from indoor space 202 butproximate to an orifice in a wall of the indoor space such a window ordoor. The illustration provided in FIG. 2 shows the sensor 206 locatedproximate to a window and within the soffit of the roof. Location asoffit of the roof and near a window will permit gas generated withinthe indoor space 202 to be measured by the sensor 206 as the gas leaksout of the window.

Referring back to FIG. 2 and FIG. 3, the sensor 154, (FIG. 1) sensor 204and 206 (FIG. 2) can be of the catalytic bead type, non-dispersiveinfrared (NDIR) thermal conductivity (TC) or other sensors built usingtechnology not yet known. :Embodiments of the invention are not limitedby the type of sensor used to detect the production of methamphetamine.

In some embodiments, more than one sensor will be deployed at a givenlocation for example, in one or more embodiments, sensor 154, sensor204, or sensor 206 will include multiple sensors. For example, acatalytic bead type sensor and a NDIR sensor could be located at 154 inFIG. 1. Such a deployment of sensors would permit measurement of a wideplurality of gases when concentrations were below the LEL as well asdetection of some gases whose concentrations exceeded the LEL and eventhe UEL. Such a sensor configuration provides greater measurementfunctionality at a given location.

FIG. 3 illustrates a plurality of sensors generally at 300, according toembodiments of the invention reference to FIG. 3, a first sensor isindicated at 304, a second sensor is indicated at 306 up to a generalnumber of n sensors indicated at 308. A controller 302 is in electricalcommunication with the sensors. Such electrical communication can beeither wired or wireless. In one or more embodiments, controller 302 isa computer based device that can control the array of sensors and adjustparameters, such as alarm level perform system tests, introduce delays,perform calibrations bypass sensors, view time histories of data,perform calculations on the acquired data and report detection ofmethamphetamine production according to algorithms described below.

In various embodiments, the controller 302 can be a supervisory controland data acquisition system interfaced to sensors 304 through 308. Insuch architectures, sensors 304 through 308 can have remote terminalunits (RTU) associated therewith to perform functions of datacollection, data coding, and data transmission to a master device in theSCADA system. A variety of sensors are commercially available forincorporation into a SCADA system such as the model 5100-2S-IT IRCombustible Gas Sensor module from Sierra Monitor Corporation.

A user interface is included to monitor data collected from the array ofsensors. The user interface can be located at 302 or at 312. In variousembodiments, 312 is a user interface that can be located remotely fromthe sensors 304 through 308 by means of a network or Internetconnection.

The array of sensors 304 through 308 can be deployed. In an area where alarge number of indoor spaces need to be monitored. For example, in amulti room house, an apartment complex, a condominium complex, apublicly accesses storage facility, a campground, etc. Data can beaccessed remotely at an alarm company facility, police station, from adevice with internet connectivity by a property owner who is away onvacation or living off site No limitation is placed on who or where themonitoring is conducted, the examples given herein are for illustrativepurposes only and do not limit embodiments of the invention.

A combustible gas sensor such a catalytic type sensor responds to allcombustible gas that burns on the sensor surface. Such a sensor willrespond to fumes given off from non-methamphetamine activities, such asusing nail polish remover to remove fingernail polish or ammonia usedfor cleaning. It is desirable to separate out signals that derive fromevery day innocuous events from signals that result from the productionof methamphetamine. In one or more embodiments, separation of suchsignals is accomplished based on combustible gas concentration level andduration of the signal. Cooking methamphetamine requires cook times thatare long compared to the durations of lawful release of combustible gassuch as use of nail polish remover or household cleaning. Combustiblegas concentration levels released during methamphetamine production aremuch larger than the lawful domestic releases of combustible gas. Thefact that explosions occur during the production of methamphetamineattests to the fact that the gas concentrations of combustible gas hasexceeded the LEI, and has risen to the combustible mixture range 112(FIG. 1A).

FIG. 4A illustrates, generally at 400, gas concentration level as afunction of time, according to embodiments of the invention. Withreference to FIG. 4A, a hypothetical combustible gas sensor collecteddata over a period of time indicated by the extent of the horizontalaxis 406. The data is displayed at 408 with gas concentration on thevertical axis 402 and time on the horizontal axis 406. The total timerepresented by the extent of the horizontal axis is two hours. Twolawful domestic releases of combustible gas are illustrated by an event410 and an event 414. These events last for several minutes and canarise from washing a window, using nail polish remover, starting a gasgrill etc. Events 410 and 414 are typically characterized by short /timedurations and are well below an LEL for the given gas. Note also the lowlevels 412 measured by the sensor before the event 410 and then measuredagain after the lawful event 410 passes. In contrast to the lawfulevent, a methamphetamine cooking event 418 k characterized by acontinuous elevated sensor output, which is above a threshold leveldetection level for methamphetamine production indicated at 404 duringthe time of the cooking.

FIG. 4B illustrates, generally at 450, a second concentration level as afunction of time, according to embodiments of the invention. Withreference to FIG. 4B, two lawful domestic releases of combustible gasare illustrated by an event 456 and an event 458. As described above,these events last for several seconds or several minutes and can arisefrom washing a window, using nail polish remover, starting a as grill,etc. Events 456 and 458 are typically characterized by short timedurations and are well below an LEL for the given gas, however theseevents can be above a threshold detection level for methamphetamineproduction indicated at 454 or in the case of FIG. 4A events 410 or 414are below the threshold detection level for methamphetamine productionindicated at 404. Note also the low levels 452 measured by the sensorbefore the event 456 and then measured again after the lawful event 456passes. In contrast to the lawful event, a methamphetamine cooking event460 is characterized by a continuous elevated sensor output during thetime of the cooking.

Methamphetamine is produced by cooking for at least 45 minutes to onehour and as long as 4 hours. A methamphetamine cooking method usingammonium nitrate takes from 45 minutes to one hour to complete. Amethamphetamine cooking method that uses red phosphorus has a minimumcooking time of 4 hours. With a priori knowledge of the time that ittakes to cook methamphetamine, a threshold time window 416 isestablished and used to program a computer to automatically detectmethamphetamine production from a combustible gas sensor's time recordas shown in FIG. 4A and FIG. 4B.

FIG. 5 illustrates, generally at 500, a method for processing datacollected from a combustible gas sensor, according to embodiments of theinvention. With reference to FIG. 5, a process starts at a block 502. Ata block 504 a concentration of combustible has is measured by acombustible gas sensor. At a block 506 the concentration is comparedagainst a threshold level. At a block 508 predefined criteria ofconcentration level and duration of the level are compared to determinewhether methamphetamine production has been detected.

FIG. 6 illustrates, generally at 600, a method for detectingMethamphetamine production, according to embodiments of the invention.With reference to FIG. 6, a process starts at a block 602. At a block604 a sensor is attached to a residential space. At as block 606 asensor measures a concentration of a combustible gas. At a block 608 acondition is reported by the sensor. The condition is related to themeasured concentration of combustible gas and can be a state of a relay,an analog value of voltage or current, etc. The process ends at a block610.

FIG. 7 illustrates, generally at 700, a block diagram of a computersystem (data processing device such as a computer, smart phone, tabletcomputer, etc.) in which embodiments of the invention may be used. Thedata processing system can be referred to as a SCADA system previouslydescribed. The data processing system can also be referred to as a dataacquisition system. The block diagram is a high level conceptualrepresentation and may be implemented in a variety of ways and byvarious architectures. Bus system 702 interconnects a Central ProcessingUnit (CPU) 704, Read Only Memory (ROM) 706, Random Access Memory (RAM)708, storage 710, display 720, audio, 722, keyboard 724, pointer 726,miscellaneous input/output (110) devices 728, and communications 730.The bus system 702 may be for example, one or more of such buses as asystem bus, Peripheral Component Interconnect (PCI), Advanced GraphicsPort (AGP), Small Computer System Interface (SCSI), Institute ofElectrical and Electronics Engineers (IEEE) standard further 794(FireWire), Universal Serial Bus (USB), etc. The CPU 704 may be asingle, multiple, or even a distributed computing resource. Storage 710may be Compact Disc (CD), Digital Versatile Disk (DVD), hard disks (HD),optical disks, tape, flash, memory sticks, video recorders, etc. Display720 might be, for example, an embodiment of the present invention. Notethat depending upon the actual implementation of a computer system, thecomputer system may include some, all, more, or a rearrangement ofcomponents in the block diagram. Thus, many variations on the system ofFIG. 7 are possible.

Connection with a network is obtained with 732 via 730, as is recognizedby those of skill in the which enables the data processing device 700 tocommunicate with devices in remote locations, in some embodiments, asensor(s) described previously in figures above, can be in communicationwith the data processing system in some embodiments, Remote TerminalUnits (RTU) are used to send data to the data processing device of FIG.7. In other embodiments, data from a sensor(s) is sent using the generalpacket radio service (GPRS) to the data processing device of FIG. 7. 732and 730 flexibly represent communication elements in variousimplementations, and can represent various forms of telemetry, GPRS.Internet, and combinations thereof.

In other embodiments, processing is accomplished locally at the sensorlocation and one or more components of the data processing device ofFIG. 7 is incorporated with the sensor to send data to a monitor andcontrol device such as a RTU or a computer device.

In various embodiments, a pointing device such as a stylus is used inconjunction with a touch screen, for example, via 729 and 728 to allow auser to run queries on data received from a sensor or sensors, sensorsin multiple locations, etc. Thus, in various embodiments, amethamphetamine detection system is implemented with a data processingdevice incorporating various components from the illustration of FIG. 7.

FIG. 8 illustrates, generally at 800, a network environment, in whichembodiments of the present invention may be implemented. The networkenvironment 800 has a network 802 that connects R remote devices 804-1through 804-R, and S sensors 808-1 through 808-S, As shown, several dataprocessing devices (computer systems, etc.) in the form of R remote804-1 through 804-R and S sensors 808-1 through 808-S are connected toeach other via a network 802, which may be, for example, a corporatebased network. Note that alternatively the network 802 might be orinclude one or more of: the Internet, a Local Area Network (LAN), WideArea Network (WAN), satellite link, fiber network, cable network, GPRS,or a combination of these and/or others. The remote devices may have,for example, disk storage systems alone or storage and computingresources. Likewise, the sensors may have in addition to combustible gassensing ability, computing and storage capabilities. The method andapparatus described herein lay be applied to essentially any type ofcommunicating means or device whether local or remote, such as a LAN, aWAN, a system bus, etc.

As described herein, embodiments of the invention can be used to detectillicit methamphetamine production. Such detection can be used to stopmethamphetamine production and to prevent loss of life and propertydamage which can be attendant upon methamphetamine production. Use ofembodiments of the invention can result in a decreased production ofmethamphetamine which can result in decreasing the dangers to societypresented by methamphetamine.

For purposes of discussing and understanding the embodiments of theinvention, it is to be understood that various terms are used by thoseknowledgeable in the an to describe techniques and approaches.Furthermore, in the description, for purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of the present invention, it will be evident however, toone of ordinary skill in the art that the present invention may bepracticed without these specific details. In some instances, well-knownstructures and devices are shown in block diagram form, rather than indetail, in order to avoid obscuring the present invention. Theseembodiments are described in sufficient detail to enable those ofordinary skill in the an to practice the invention, and it is to beunderstood that other embodiments may be utilized and that logical,mechanical, electronical, and where changes may be made withoutdeparting from the scope of the present invention,

Some portions of the description may be presented in terms of algorithmsand symbolic representations of operations on, for example, data bitswithin a computer memory. These algorithmic descriptions andrepresentations are the means used by those of ordinary skill in thedata processing arts to most effectively convey the substance of theirwork to others of ordinary skill in the art. An algorithm is here, andgenerally, conceived k be a self-consistent sequence of acts leading toa desired result. The acts are those requiring physical manipulations ofphysical quantities. Usually, though not necessarily these quantitiestake the form of electrical or magnetic signals capable of being stored,transferred, combined, compared, and otherwise manipulated. It hasproven convenient at times, principally for reasons of common usage, torefer to these signals as bits, values, elements, symbols, characters,terms, numbers, or the like.

It should be borne in mind, however, that all of these and similar termsare to be associated with the appropriate physical quantities and aremerely convenient labels applied to these quantities. Unlessspecifically stated otherwise as apparent from the discussion, it isappreciated that throughout the description, discussions utilizing termssuch as “processing” or “computing” or “calculating” or “determining” or“displaying” or the like, can refer to the action and processes of acomputer system, or similar electronic computing device, thatmanipulates and transforms data represented as physical (electronic)quantities within the computer system's registers and memories intoother data similarly represented as physical quantities within thecomputer system memories or registers or other such information storage,transmission, or display devices.

An apparatus for performing the operations herein can implement thepresent invention. This apparatus may be specially constructed for therequired purposes, or it may comprise a general-purpose computer,selectively activated or reconfigured by a computer program stored inthe computer. Such a computer program may be stored in a computerreadable storage medium, such as, but not limited to, any type of diskincluding floppy disks, hard disks, optical disks, compact disk.- readonly memories (CD-ROMs), and magnetic-optical disks, read-only memories(ROMs), random access memories (RA s), electronically programmableread-only memories (EP ROM)s, electrically erasable programmableread-only memories (EEPROMs). FLASH memories, magnetic or optical cards,etc., or any type of media suitable for storing electronic instructionseither local to the computer or remote to the computer.

The algorithms and displays presented herein are not inherently relatedto any particular computer or other apparatus. Various general-purposesystems may be used with programs in accordance with the teachingsherein, or it may prove convenient to construct more specializedapparatus to perform the required method. For example, any of themethods according to the present invention can be implemented inbard-wired circuitry, by programming a general-purpose processor, or byany combination of hardware and software. One of ordinary skill in theart will immediately appreciate that the invention can be practiced withcomputer system configurations other than those described, includinghand-held devices, multiprocessor systems, microprocessor-based orprogrammable consumer electronics, digital signal processing (DSP)devices, set top boxes, network PCs, minicomputers mainframe computers,and the like. The invention can also be practiced in distributedcomputing environments where tasks are performed by remote processingdevices that are linked through a communications network.

The methods herein may be implemented using computer software, ifwritten in a programming language conforming to a recognized standard,sequences of instructions designed to implement the methods can becompiled for execution on a variety of hardware platforms and forinterface to a variety of operating systems. In addition, the presentinvention is not described with reference to any particular programminglanguage. It will be appreciated that a variety of programming languagesmay be used to implement the teachings of the invention as describedherein. Furthermore, it is common in the art to speak of software, inone form or another (e.g. program, procedure, application, driver, , . .), as taking an action or causing a result. Such expressions are merelya shorthand way of saying that execution of the software by a computercauses the processor of the computer to perform an action or produce aresult.

It is to be understood that various terms and techniques are used bythose knowledgeable in the art to describe communications, protocols,applications, implementations, mechanisms, etc. One such technique isthe description of an implementation of a technique in terms of analgorithm or mathematical expression. That is, while the technique maybe, for example, implemented as executing code on a computer, theexpression of that technique may be more aptly and succinctly conveyedand communicated as a formula, algorithm, or mathematical expression.Thus, one of ordinary skill in the aft would recognize a block denotingA+B=C as an additive function whose implementation in hardware and/orsoftware would take two inputs (A and B) and produce a summation output(C). Thus, the use of formula, algorithm, or mathimatically expressionas descriptions is to be understood as having a physical embodiment inat least hardware and/or software (such as a computer system in whichthe techniques of the present invention may be practiced as well asimplemented as an embodiment).

A machine-readable medium is understood to include any mechanism forstoring or transmitting information in a form readable by a machine(e.g., a computer). For example, a machine-readable medium includes readonly memory (ROM); random access memory (RAM), magnetic disk storagemedia; optical storage media; flash memory devices; electrical, optical,acoustical or other form of non-transitory propagated signals carrierwaves, infrared signals, digital signals. etc.): etc.

As used in this description, “one embodiment” or “an embodiment” orsimilar phrases means that the feature(s) being described are includedin at least one embodiment of the invention. References to “oneembodiment in this description do not necessarily refer to the sameembodiment; however, neither are such embodiments mutually exclusive.Nor does embodiment” imply that there is but a single embodiment of theinvention. For example, a feature, structure, act, etc. described in“one embodiment” may also be included in other embodiments. Thus, theinvention may include a variety of combinations arid/or integrations ofthe embodiments described herein.

While the invention has been described in terms of several embodiments,those of skill in the art will recognize that the invention is notlimited to the embodiments described, but can be practiced withmodification and alteration within the spirit and scope of the appendedclaims The description is thus to be regarded as illustrative instead oflimiting.

What is claimed is:
 1. A system to detect methamphetamine production ina residential building, comprising: a sensor, the sensor outputs asignal in response to detection of a concentration of a gas:, and aprocessor, the processor is electrically coupled to receive the signaland to process the signal to separate an event from a background level,the processor to compare a duration of the event to the threshold timewindow value, wherein two states result: (1) if the duration of theevent is equal to or greater than the threshold time window value apossible methamphetamine production detection is made independently ofgas concentration existing above the background level during the event,and a warning signal is generated; or (2) if the duration of the eventis not equal to or greater than the threshold time window value then anon-methamphetamine production activity i detected and the earningsignal is not generated.
 2. The system of claim 1, wherein the sensor isa combustible gas detector.
 3. The system of claim 2, wherein the sensoris a catalytic sensor.
 4. The system of claim 2, wherein the sensor isan infrared sensor.
 5. The system of claim 2, wherein the sensorresponds to volatile organic compounds.
 6. The system of claim 1,further comprising: a second sensor, the second sensor is electronicallycoupled to the processor, the second sensor outputs a second signal inresponse to detection of a concentration of the gas at any volumepercentage of the gas, the processor uses the second signal duringseparation of the event from the background level.
 7. The system ofclaim 1, further comprising: a communication link, the communicationlink is coupled to the processor, the communication link to facilitatemessage transmission responsive to the signal.
 8. The system of claim 1,wherein the warning signal is generated when the threshold time windowvalue is greater than several minutes and less than 45 minutes long. 9.The system of claim 8, wherein the warning signal is generated when thethreshold time window value is approximately 15 minutes long.
 10. Asystem for execution by a data processing system to detect a gasreleased during production of methamphetamine in a residential building,comprising: means for measuring a concentration of a has with acombustible has sensor; means for analyzing the concentration toidentify an event; means for identifying a non-methamphetamineproduction activity when a duration of the event is less than a durationof a threshold time window value; and means for identifying a possiblemethamphetamine production detection when the duration of the event isequal to or greater than the threshold time window value.
 11. The systemof claim 10, wherein the concentration is approximately equal to 50parts per million (ppm).
 12. The system of claim 10, further comprising:means for analyzing a system status to determine whether tampering hasoccurred.
 13. The system of claim 10, further comprising: means forgenerating a warning signal when a duration of an event is greater thanseveral minutes and less than 45 minutes long.
 14. The system of claim10, wherein the threshold time window value is greater than severalminutes.
 15. The system of claim 10, wherein the means for measuring ismade with a technology selected from the group consisting of Metal OxideSemiconductor, Galvanic Cell, and Electrochemical.
 16. The system ofclaim 10, wherein the combustible gas sensor is a volatile organiccompound sensor.
 17. A computer readable storage medium storingexecutable computer program instructions for causing the data processingsystem to perform steps comprising: receiving a signal from acombustible gas sensor, the combustible gas sensor is attachable to aresidential building; analyzing the signal to identify an event, whereinthe event occurs independently of gas concentration; identifying anon-methamphetamine production activity when a duration of the event isless than a duration of a threshold time window value; and identifying apossible methamphetamine production detection when the duration of theevent is equal to or greater than the threshold time window value. 18.The computer readable storage medium of claim 17, further comprising:analyzing a. system status to determine whether tampering has occurred.19. The computer readable storage medium of claim 17, wherein thecombustible gas sensor is a volatile organic compound sensor.
 20. Thecomputer readable storage medium of claim 17, wherein the threshold timewindow value is several minutes long.
 21. The computer readable storagemedium of claim 17, wherein the combustible gas sensor is made with atechnology selected from the group consisting of Metal OxideSemiconductor, Galvanic Cell, and Electrochemical.